Advice on concrete for cable tray installation

[skyzone]

Hi,

New here so I apologize if this question is in the wrong forum. I'm quoting on a job to cable a new data center. 78 drops in 19 cabinets in two rows. The room is 18'x75' and cabinets will be placed width wise. Up to 200 cables will be expanded at a later date for the remaining room.

I think placing a ladder cable tray down the center of the room will accommodate future expansion. However, I have never installed a cable tray before so I need to know what things to think about regarding drilling into the overhead concrete.

Any suggestions?

Thanks

 

[misseditbythatmuch]

There is actually some real engineering that needs to go into a project like this. For example, what kind of concrete is overhead? Is it pre-cast elements or cast in place? There is a big difference between 2,000 psi and 5,000 psi concrete. Are there any structures listed on the as-built plans embedded in the concrete that you need to avoid? Is the concrete fully cured? What kind of anchors will you use? I prefer to embed threaded rod in a hole filled with anchoring epoxy (Such as a Sika brand product).

You will need to be sure that the tracking you use is rated for the full fill capacity you will be certifying it for. Then, your anchoring system must meet the track's rating for each attachment point. You must also allow for both static and dynamic loads. Dynamic comes into play during cable pulls as well as any potential ladders or other loads that may be placed against the tracks and any building codes regarding movement loads due to earth tremor(if you are in a fault area).

In summary, before drilling into the overhead concrete, you should have calculated the dynamic and static loads and confirmed the building code before you select a fastening system. Then, you must be sure that the fasteners used are installed according to manufacturer's specs (Some fasteners should not be used in still-curing concrete, some bonding agents must be used in holes that have been air blasted clean, drilled to a precise depth and only in a certain humidity range, etc.) It also matters with some systems as to what type of drill bit you use (some fasteners require a tight tolerance hole that requires a high-quality very hardened hammer drill bit. You must avoid drilling into existing embedded structures (see the as-built plans). Of course, you must be sure to place the tracking where the drops will be in place but also using a transit or laser guide to ensure that you do not mis-align struts or threaded rod which will hugely reduce holding strength.

Of course, never attach tracking to other support structures (HVAC or Conduit runs) as your structure loads were not contemplated when those other structures were calculated and installed.

Just some thoughts to get you started.

Last, but not least, remember, if you fail to install correctly, and it comes down, you will be responsible for a lot of property damage, or worse, serious injury.

 

[skyzone]

Thanks for the info, I'm glad I asked.

I just got text from the customer on the concrete type and this is what he had to say...

"It's suspended slab with pretensiond cables embedded in the concrete. There are hollow tubes running through those slabs with the cables embedded in."

I think I should leave this up to the professionals. Any idea the rates a contractor would charge just to drill the holes and put in the rods?

 

[ANFPS26]

Can't you install cable duct work on top of the cabinets? I personally would not drill a concrete ceiling that is attached the way you describe. What if they drill through a suspension cable? The cables are engineered to support the concrete weight. Adding more weight may not be a good idea. Perhaps a structural engineer should be consulted.

Jim

 

[skyzone]

I've never seen cable management on top of the cabinets before. Is there such a thing? It's eventually going to be in a grid with additional rows of 18'

 

[SYQUEST]

You have not mentioned it yet, do you have a raised floor? Typically, data centers use a raised floor and most cable systems are placed there. That would simplify the whole approach and requirements possibly?

....JIM....

 

[skyzone]

No raised floor. Shaw would be actually coring into the floor to bring in two fibers from off the street. Running it from underneath would not be possible.

 

[trvlr1]

Another option ... instead of suspending from the ceiling, can you mount it to the top of the racks that will be in place? Threaded rod will lift it away from the rack so you don't mess up the ventilation if that is a concern.

 

[ANFPS26]

Also, perhaps you could support the ladder rack between cabinets on stanchions from the floor.

Jim

 

[SYQUEST]

Besides, being supported from the tops of the racks and cabinets, it could go from wall to wall, depending on layout and seismic requirements.

....JIM....